The present invention relates generally to separable connector modules for electrical power cables and relates particularly to a type of module commonly used in high voltage underground electric power distribution systems to connect the cables and operating components of such a system.
Separable connector modules are used in pairs, with one module being a rod module with a contact rod and the other module being a bore module with a receiving bore for the rod of the rod module and with a set of receiving contacts in the bore which firmly grasp the rod to make contact.
Separable connector pairs are frequently disconnected while energized, despite certain arcing hazards which are generally known to be associated with such a loadbreak procedure. One such hazard has to do with the escape from the bore module of ionized conductive gases. A loadbreak disconnection results in arcing between the rod and the receiving contact inside the bore. The arcing causes rapid generation of gases in the bore. The generation of these gases is largely by design, for these gases quench the arcing to permit the disconnection to be completed. However, upon the removal of the rod from the bore, excessive ionized gases inside the module may rush out of the bore and establish a conductive path between the energized contacts and a ground plane, such as the grounded shielding of the cable or connector modules. This would result in a line-to-ground short circuit.
In present connector modules, a hinged-gate gas-trap valve is mounted at the outer end of the bore module to immediately seal shut the bore as soon as the rod is withdrawn, thereby preventing the escape of excessive volumes of ionized gas. Such a device is disclosed and claimed in U.S. Pat. No. 3,763,461 and assigned to the same assignee as this invention.
While that gas-trap valve is effective in preventing escape of the gas, it adds significantly to the longitudinal dimensions of the module. This is a definite disadvantage, since such modules are typically used in close quarters, such as in a distribution transformer cabinet, where the longitudinal dimension is particularly critical. Furthermore, the asymmetrical configuration of the valve, especially the presence of a metal spring to only one side of the valve opening for the hinged gate, can lead to undesirable field stresses at higher voltage ratings, such as at 23.5 kilovolts.